Minkowski vacuum in Rindler spacetime and Unruh thermal state for Dirac fields

We consider a free Dirac field in flat spacetime and we derive the representation of the Minkowski vacuum as an element of the Rindler-Fock space. We also compute the statistical operator obtained by tracing away the left wedge. We detail the resulting thermal state for fermionic particles.


Launching optical tsunamis against tumor cells

We demonstrate the excitation of giant rogue waves of light inside human pancreatic tumor cells; they can be used for deep light transport and local heating for cancer treatment.

Rogue waves are intense and unexpected wavepackets ubiquitous in complex systems. In optics, they are promising as robust and noise-resistant beams for probing and manipulating the underlying material. Localizing large optical power is crucial, especially in biomedical systems, where extremely intense beams have not yet been observed. We here discover that tumor-cell spheroids manifest optical rogue waves when illuminated by randomly modulated laser beams. The intensity of light transmitted through bio-printed three-dimensional tumor models follows a signature Weibull statistical distribution, where extreme events correspond to spatially-localized optical modes propagating within the cell network. Experiments varying the input beam power and size indicate that rogue waves have a nonlinear origin. We show these optical filaments form high-transmission channels with enhanced transmission. They deliver large optical power through the tumor spheroid, which can be exploited to achieve a local temperature increase controlled by the input wave shape. Our findings shed new light on optical propagation in biological aggregates and demonstrate how extreme event formation allows light concentration in deep tissues, paving the way to using rogue waves in biomedical applications such as light-activated therapies


Frame-dependence of the non-relativistic limit of quantum fields

We study the non-relativistic limit of quantum fields for an inertial and a non-inertial observer. We show that non-relativistic particle states appear as a superposition of relativistic and non-relativistic particles in different frames. Hence, the non-relativistic limit is frame-dependent. We detail this result when the non-inertial observer has uniform constant acceleration. Only for low accelerations, the accelerated observer agrees with the inertial frame about the non-relativistic nature of particles locally. In such a quasi-inertial regime, both observers agree about the number of particles describing quantum field states. The same does not occur when the acceleration is arbitrarily large (e.g., the Unruh effect). We furthermore prove that wave functions of particles in the inertial and the quasi-inertial frame are identical up to the coordinate transformation relating the two frames.